Pyrithione acid (1-hydroxy-2-pyridinethione) and various salts thereof are well-known biocides exhibiting broad spectrum anti-bacterial and anti-fungal activity. Illustrative applications are disclosed, for example, in U.S. Pat. No. 4,818,436 which discloses the use of pyrithiones in metal working fluids, and U.S. Pat. No. 4,935,061 which discloses their use in paints. Zinc pyrithione is widely used in hair care products such as shampoos.
The use of fabric treating articles and processes in clothes driers is also well-known in the art. For example, U.S. Pat. No. 4,073,996 discloses the use of various flexible substrate articles in clothes driers during the clothes-drying cycle in order to impart desired characteristics to the clothing being dried. Also, the '996 patent discloses the direct addition of desired additives from a spray device (e.g., an aerosol can, mechanical spray pump, or the like) using a carrier such as a propellant and/or solvent, alone or in the presence of other optional additives, such as finishing aids, fumigants, lubricants, fungicides, and sizing agents (see column 8, lines 34-35 of the '996 patent). However, no specific biocides are disclosed in this patent.
British Pat. No. 1,390,004 has shown that the addition of zinc pyrithione, in an aqueous solution of a quaternary ammonium compound during the rinse cycle of a laundering operation, results in a high degree of anti-microbial activity. However, this methodology is more expensive than might be desired since significant amounts of the zinc pyrithione are carried away with the rinsate during the rinse cycle.
U.S. Pat. No. 4,443,222 discloses the application of zinc pyrithione to cellulosic textiles by first solubilizing the zinc pyrithione in a polyamine and urea, and then impregnating the cellulosic textile with the resulting solution, and then heating the clothing to cause a specific reaction with the impregnating chemicals. This patent claims the resulting anti-microbial activity is durable to laundering. However, due to its complexity, this is not a method which lends itself to home use by a consumer on an as-needed basis.
Heretofore, there has been no disclosure in the prior art to the knowledge of the present inventors of the use of pyrithione acid, or salts thereof, as a drier-cycle additive to provide biocidal efficacy for clothing.